Carbon Nanotube Growth from Nickel and Nickel-Silicide Nanoparticles Created Via Dewetting of Thin Films
Class
Article
Department
Mechanical and Aerospace Engineering
Faculty Mentor
Nicholas Roberts
Presentation Type
Oral Presentation
Abstract
In the past couple decades, carbon nanotubes (CNTs) have become an increasingly more prevalent topic in materials research due to enhanced mechanical, electrical and thermal properties. The growth mechanisms of CNTs are somewhat understood, however, we still lack the ability to fine tune all of the structural variables of CNTs grown via the common growth methodology of chemical vapor deposition (CVD). These structural variables depend on a large parameter space (i.e. temperature, catalyst, substrate, etc.) but are the determining factors in the eventual mechanical, thermal and electrical properties. This indicates that more effort needs to be put into characterizing the effect of CVD/substrate parameters on CNT structure. Here the effect of the substrate/catalyst will be analyzed. There are two commonly used mechanisms for CNT growth. One is the vapor-liquid-solid (VLS) mechanism, usually seen with metal catalysts for growth, where the catalytic particles are in the liquid phase during growth and consequently exhibit an amorphous mass as a template structure. Another method is the vapor-solid-solid (VSS) mechanism, usually seen with semiconducting nanoparticles for growth, where the catalytic particle is in the solid phase and consequently has a crystal structure as a template for growth. By exhibiting this crystal structure template, the VSS mechanism may provide a pathway for directed growth and control over CNT structural properties such as diameter and chirality. This particular study looks at growth from both nickel particles (VLS mechanism) and from nickel-silicide particles (VSS mechanism). Particle arrays are created via dewetting of 1-2 nm thick nickel films or bi-layer films of nickel and silicon. The particle arrays are then characterized for diameter and pitch distributions using atomic force microscopy (AFM). CNTs are grown on the nano-particle arrays using a CVD process and subsequently characterized using scanning electron microscopy (SEM) and Raman spectroscopy.
Start Date
4-9-2015 3:00 PM
Carbon Nanotube Growth from Nickel and Nickel-Silicide Nanoparticles Created Via Dewetting of Thin Films
In the past couple decades, carbon nanotubes (CNTs) have become an increasingly more prevalent topic in materials research due to enhanced mechanical, electrical and thermal properties. The growth mechanisms of CNTs are somewhat understood, however, we still lack the ability to fine tune all of the structural variables of CNTs grown via the common growth methodology of chemical vapor deposition (CVD). These structural variables depend on a large parameter space (i.e. temperature, catalyst, substrate, etc.) but are the determining factors in the eventual mechanical, thermal and electrical properties. This indicates that more effort needs to be put into characterizing the effect of CVD/substrate parameters on CNT structure. Here the effect of the substrate/catalyst will be analyzed. There are two commonly used mechanisms for CNT growth. One is the vapor-liquid-solid (VLS) mechanism, usually seen with metal catalysts for growth, where the catalytic particles are in the liquid phase during growth and consequently exhibit an amorphous mass as a template structure. Another method is the vapor-solid-solid (VSS) mechanism, usually seen with semiconducting nanoparticles for growth, where the catalytic particle is in the solid phase and consequently has a crystal structure as a template for growth. By exhibiting this crystal structure template, the VSS mechanism may provide a pathway for directed growth and control over CNT structural properties such as diameter and chirality. This particular study looks at growth from both nickel particles (VLS mechanism) and from nickel-silicide particles (VSS mechanism). Particle arrays are created via dewetting of 1-2 nm thick nickel films or bi-layer films of nickel and silicon. The particle arrays are then characterized for diameter and pitch distributions using atomic force microscopy (AFM). CNTs are grown on the nano-particle arrays using a CVD process and subsequently characterized using scanning electron microscopy (SEM) and Raman spectroscopy.